High-sensitivity magnetometry based on quantum beats in diamond nitrogen-vacancy centers.

Area of Science:

• Quantum sensing
• Diamond magnetometry
• Solid-state physics

Background:

• Nitrogen-vacancy (NV) centers in diamond are promising quantum sensors.
• Existing magnetometers are susceptible to environmental fluctuations like temperature and strain.
• Improving sensitivity and robustness is crucial for advanced magnetic field measurements.

Purpose of the Study:

• To demonstrate an absolute magnetometer immune to temperature and strain.
• To enhance magnetic field sensitivity using quantum beats in NV ground states.
• To investigate the performance of this technique for single NV centers and ensembles.

Main Methods:

• Utilizing quantum beats in the ground state of nitrogen-vacancy centers.
• Eliminating dependence on zero-field splitting (D) for environmental immunity.
• Employing a single NV center near the diamond surface for low-frequency noise measurement.
• Applying the technique to NV center ensembles to mitigate dephasing.

Main Results:

• Achieved photon-shot-noise limited sensitivity of 38 nT/sqrt[Hz] with a single NV center.
• Demonstrated up to a factor of 15 improvement in magnetic sensitivity for long acquisition times.
• Showcased robustness against thermal drifts and strain inhomogeneity.
• Observed a factor of 2.3 improvement in sensitivity for NV ensembles by eliminating strain dephasing.

Conclusions:

• The quantum beat magnetometer offers immunity to temperature and strain, enhancing absolute measurement capabilities.
• This technique significantly improves magnetic sensitivity and robustness, outperforming traditional two-level spin implementations.
• The method is effective for both single NV centers and ensembles, paving the way for advanced quantum sensing applications.